Training Guide
Electrolytes & Hydration: What You Need During Exercise
Sweating out water isn't the only thing happening during a hard workout — here's why electrolytes matter, and when plain water isn't enough.
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What Electrolytes Actually Are
Electrolytes are minerals that carry an electrical charge in your body's fluids — primarily sodium, potassium, magnesium, calcium, and chloride. They regulate fluid balance, allow nerves to send signals, and enable muscles (including your heart) to contract properly.
When you sweat, you lose water and electrolytes together, primarily sodium and, to a lesser degree, potassium. Replacing only the water and none of the electrolytes can actually make dehydration and cramping worse, not better.
Why Water Alone Isn't Always Enough
During short, low-intensity activity, plain water does the job fine. But during prolonged or intense exercise — especially in heat — sweat losses can add up to over a liter per hour, carrying meaningful sodium losses with it.
Drinking large volumes of plain water without replacing sodium can dilute the sodium concentration in your blood, a condition called hyponatremia. In endurance events, this is a real and sometimes serious risk — not just a marketing point for sports drinks.
Signs You Need More Than Water
- Muscle cramping during or after exercise, especially in longer sessions
- Exercise lasting longer than 60-90 minutes, particularly in heat or humidity
- Heavy, visible sweating or salt residue left on skin and clothing after training
- Dizziness, headache, or unusual fatigue during a workout despite drinking water
- Training twice in one day, which compounds fluid and sodium losses
The Key Electrolytes
Sodium
The primary electrolyte lost in sweat, and the one that matters most for hydration during exercise. It helps your body retain the water you drink rather than losing it straight through urine.
Potassium
Works alongside sodium to regulate fluid balance and muscle contraction. Losses are smaller than sodium but still meaningful during prolonged sweating.
Magnesium and Calcium
Both support muscle contraction and relaxation; low levels of either are commonly linked to exercise-related cramping.
How Much You Actually Need
For workouts under an hour at moderate intensity, water is usually sufficient. Once you're training longer than 60-90 minutes, sweating heavily, or exercising in the heat, aim to replace roughly 300-700 mg of sodium per hour, alongside your fluids — either through an electrolyte drink mix, salted foods, or an electrolyte supplement.
Choosing an Electrolyte Product
Not all sports drinks and electrolyte mixes are equal. Look for:
- Meaningful sodium content: at least 200 mg per serving — many popular sports drinks are surprisingly low in sodium
- Low added sugar: many mixes pack unnecessary sugar; you don't need a lot of carbs for hydration alone unless the session is also long and calorie-demanding
- A mix of minerals: sodium plus potassium, magnesium, and/or calcium covers more ground than sodium alone
- No artificial fillers: simpler ingredient lists are generally preferable for something you're using regularly
The Bottom Line
For short or casual workouts, water is all you need. Once training gets longer, hotter, or sweatier, electrolytes — sodium especially — become just as important as the water itself. Matching your hydration strategy to the actual demands of your training, rather than defaulting to plain water for everything, is what actually prevents cramping and keeps performance from dropping late in a session.